Outer flat drill rod is applicable in special well drilling and oilfield maintenance. A pipe upsetting treatment is employed for the pipe body to ensure that the outer diameter of thickened end, the joint outer diameter, and the outer diameter of pipe is the same.

Features
a. The outer flat structure is helpful when it comes to handling some accidents like well collapse.
b. The special connection method with thread will make up for the anti-torque strength reduction caused by the reduction of outer diameter.
c. It is applicable in slim hole drilling, oil well drilling, small radius horizontal well drilling, vertical drilling rig, and CBM well drilling.
d. Available specification: 2-3/8, 2-7/8, 3-1/2, 4, 4-1/2, and 5.

This is a patented product in Caston. Our inner flat drill rod adopts a special upsetting technique to increase the inner diameter of the thickened area. The inner diameter of thickened end, joint, and pipe body is kept to be the same.

Advantages
a. Pressure loss is reduced by 20%-50%.
b. The hydraulic efficiency and drilling speed is largely improved.
c. The inner flat structure helps to reduce erosion, improve drill rod's fatigue resistance, and extend the drill pipe's life.
d. The internal stress concentration of the thickened area is largely reduced.
e. The inner flat drill rod is applied in continuous coring and rope coring.

In the drilling process, heavy weight drill pipe (HWDP) is used for making the transition between rigid drill collars and flexible drill pipes.

Advantages
a. Reducing the stress concentration between drill pipe and drill collar
b. Preventing differential pressure pipe sticking
c. Avoiding excessive buckling in the intermediate thickened part

Specification: 2-7/8 –6-5/8;
Structure: welded/integral;
Type: common heavy weight drill pipe, spiral heavy weight drill pipe;
Thread type: API NC31, NC38, NC40, NC46, NC50, 5-1/2FH, and 6-5/8FH
Standards of pipe upsetting: APISPEC7-1 and APISPEC7-2

Quality Control Standards
a. The drill pipe body and joints are of high impact toughness and fatigue resistance
b. Stress relief groove and reaming structure is set to reduce stress concentration and improve fatigue resistance
c. Inspection for rod body: 100%FLUT+100%MPI; inspection for joints and welded region: 100%UT+100%MPI

Modified Performance
1. The joints of heavy weight drill pipe is given buckle installing and removal test to ensure the buckle works well
2. Thread cold rolling technique is adopted to enhance thread's hardness
3. A wear resistant area is welded additionally on the joints to reduce the wear and tear of some vital parts
4. To prevent corrosion and aging, the inner wall of drilled hole is coated with an anti-acid anti-corrosion layer to reduce cost

As the development of deep hole drilling, ultra deep hole drilling, and air drilling techniques, the security requirements on drill collar is becoming higher and higher. With light weight and little resistance, Aluminum drill pipe has been used in more and more fields.
Besides, it is worth mentioning that, Caston Aluminum drill pipe has been successively applied in the SG-3 ultra-deep well in Kola Peninsula.

Applications
a. Horizontal well drilling
b. Deep hole drilling: to reduce the load of drill rig, and increase rig's max drilling depth
c. Oil well with hydrogen sulfide and other corrosive medium

Advantages (Comparing with steel drill pipes)
a. In general, the saved cost of applying Aluminum drill pipe is far greater than the initial high purchase cost.
b. With the wet weight of Aluminum alloy reducing by 50%, and that of drill pipe reducing by 30%, the drilling capacity of drill pipe is largely improved.
c. The excellent horizontal directional drilling capacity makes the drill pipe more suitable for directional well and extended reach well.
d. About 20%-30% of torque, resistance, and water loss is saved.
e. Aluminum alloy can effectively prevent hydrogen sulfide and carbon dioxide corrosion.
f. Aluminum drill pipe is of no magnetic. It is easy operated and won't hurt casings.

Drill collar is a kind of thick-walled pipe used in drilling process.To meet the deep-hole drilling needs and adapt to complex geological environment, Caston has especially developed a series of patented products. The special thread and high grade steel makes them applicable in various harsh environments like high torsion resistance, sulfur containing, and extremely cold.
Dimension: 3-1/8' – 11'
Type: round drill collar, spiral drill collar, non-magnetic drill collar
Standards: API SPEC7-1, API SPEC7-2, API RP 7G